Although I hadn't seen him for years, I______his voice on the telephone at once.
A. realized
B. recognized
C. heard
D. discovered
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So fast______that it is difficult for us to imagine its speed.
A. light travels
B. travels light
C. does light travels
D. does light travel
The Americans and the British not only speak the same language but also ______ many social
A. join
B. share
C. create
D. maintain
In construction, the Romans made extensive use of______.
A. iron ore
B. geometry and trigonometry
C. Greek mathematical thought
D. both B and C
It can be inferred from the passage that______.
A. light waves could be used in a device similar to radar
B. radar was a practical application of a well-known principle
C. radar gready increased the effectiveness of the Royal Air Force
D. sound waves are reflected from a hillside under all conditions
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